Busted: Monk uses needle to break, but not bust through, piece of glass

There’s been a video circling around online this past month of a Shaolin monk throwing a needle at a pane of glass, breaking the glass with its tiny point.

Shaolin monks have long been training to break glass with thrown needles, so the feat itself is nothing new—although it is impressive, as the monks reportedly train for almost a decade to master this skill.

But the new YouTube video posted by a duo of dudes called The Slow Mo Guys now captures the epic action in slow motion.

I won’t deny that everything looks cooler in slow motion (like bursting Prince Rupert’s drops), but I have a gripe with the new video and all the hype swirling around it—nearly all the headlines and coverage indicate that the Shaolin master throws the needle through glass.

After watching the video the first time, I thought I must have missed something.

So I watched it again.

But the encore viewing brought me to the same conclusion—the needle doesn’t go through the glass, but instead bounces off the front of the pane after impact. It seems obvious, right?

And yet headline after headline claimed that he threw the needle through the glass.

I even checked the definition of the word through: “moving in one side and out of the other side of.” Just nope.

As a final check, I consulted glass expert John Mauro to make sure I wasn’t missing something.

In addition to being a knowledge source on glass science, Mauro has experience setting the record straight—so when he watched the video and confirmed my assessment that the needle doesn’t go through the glass, I was finally convinced.

“But the monk is throwing it with enough force and at the proper angle to maximize the amount of stress upon impact,” Mauro writes via email. “This creates tensile forces on the opposite face of the glass, which cause it to break. Many small, sharp shards of glass are ejected from the opposite side due to these tensile forces—it is these glass shards that pop the balloon, not the needle.”

In the feat of breaking glass, what the needle does have going for it is that its small point is able to concentrate force in a very small area, maximizing the damage it can do to the glass. But throwing that small point with enough force and the proper angle is the tricky part—and that’s where the monk’s years of training come into the equation.

But there’s another interesting thing about the video, Mauro notes. The Slow Mo Guys got something else wrong, too—they used too slow of a camera to appropriately capture the glass-breaking action.

The V2511 camera used for the slow-motion frames in the YouTube video captured the needle-throwing stunt at 28,500 frames per second. But, Mauro notes, you would need a camera that can capture 500,000 frames per second to really see how the glass breaks upon impact.

And he would know—in 2014, Mauro and a group of scientists then at Corning published a paper in Applied Physics A in which they used video footage captured at 500,000 frames per second to map how strengthened glass breaks upon impact.

I guess The Slow Mo Guys should have done a literature review first.

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